同步发电机pscad详细建模过程

SynchronousMachineStudy?1MethodsofInitializingaSynchronousMachineMotivation:TheobjectiveofthisapplicationnoteistofamiliarizetheuserwiththesynchronousmachinemodelinPSCADanddemonstratevariousmethodsofinitializingthesynchronousmachinetoreachaspecificloadflowsteadystatecondition.SystemOverview:Inordertoinvestigatetheeffectofvariousphenomenasuchasfaultsetcinthesystem;itiscrucialthatthesystemisinitializedproperlyandisunderpropersteadystateloadflowconditions?InPSCADtherecommendedmethodofinitializingthemachineistostartitasafixedvoltagesourceandusethismodeofoperationtodetermineexciterandgovernorinput(orfieldvoltageandmechanicaltorque)parametersneededtoproducethedesiredsteadystateloadflowcondition.Note:ThesynchronousmachinemodelinPSCADprovidesuserswiththeoptionofrunningitaspuresourceThemodelalsoprovidestheoptionofrunningitatafixedspeedof1PU(withthemechanicaldynamicsdisabled).Illustration#1-Machinemodelwithoutcontrollers(exciter/governor)错误!未找到引用源。showsaverysimplecasetoillustratetheloadflowinitializationofthenetworkwhenamachinemodelisusedinthesimulation?Forsimplicity,machinecontrolssuchasexcitersandgovernorsarenotineludedinthismodel.Figure1:PSCADmodeltostudytheinitializationofsynchronousmachine(PSCADcaseSMstudyOlA.pscx)Attimet=0,machineisrunasapuresourcewithitsterminalvoltagemagnitudeandphasespecifiedbytheuser.Tooperatethemachineasapuresourcesettheinitialconditionoptionintheparameterto'none：asshowninFigure2.Bydoingsotheusercanspecifytheterminalvoltageconditionsaloneandproperlyinitializethemachineandthenetworktoaspecificloadflow.o-JSynchronousMachine1.^5SyTKhroncxjsMachineFigure2:InitialconditionoptionavailableinPSCADThevariableinitializationcontrol(S2M)specifiesthetimeatwhichthemodeltransitionsfromsourcetoanormalmachinewithallitselectricalequations’active".Toensurethatthemachineisoperatingasasource,the'variableinitializationcontrol(S2M)hastobesetto9"untiltherequiredsteadystateconditionisattained.Inthisexample,thesignal"S2I7Tissettochangeitsstatefrom0to1attimet=2s(Figure3).AttheinstantthesignalS2Mswitchesfrom0to1,themodelactsasanormalsynchronousmachinebutwiththemachinespeedfixedat1PU.TheoutputsignalTfO*isthe"initialized'fieldvoltageofthemachinethatwouldbenecessarytoholdthemachine'ssteadystateoperation?AttheinstantZS2MZchangesstate,thevalueof’EfO"issampledandisprovidedasaconstantfieldvoltageinputtothemachine'sfieldwinding.Ifnecessary,theusermayrunthesimulationforafurtherdurationatconstantspeed,allowingsmalltransientsthatmayoccuratS2Mtransitiontodecaybefore'releasing"therotormechanicaldynamics?Inthisexample,therotordynamicsare"unlocked'att=2.5swherethesignalLRRtransitionsfrom0to1.Theoutputsignal'TmO'isthe"initialized"mechanicaltorquethatwouldbenecessarytoholdthemachine"ssteadystateoperation.AttheinstantLRRchangesstate,thevalueof'TmO'issampledandisprovidedasaconstantinputtothemachine'smechanicalinputfield'Tm'?ajSynchronousMochneVinGrgpiiFigure3:SwitchingfromsourcemodetomachinemodeandenablingtherotordynamicsSimulationResultsFigure4showsthevariationofthemachineparameterswhenitisswitchedfromsourcetomachinemodeatt=2secandalsowhentherotorisreleasedatt=2.5sec?G'RDg&吕EDA-euElsFigure4:SimulationresultsREALRZWER50/-?????????????????????........................??..---20?f匸aSs■n■■in,■REACT2EROWS?ao■70■An.50■13040?J—?n??in.0?10■Illustration#2-Machinemodelwithexciter,governorandturbinemodelsinthesimulation.Foramorerealisticsimulation,theexcitersandgovernorsandturbinemodelsshouldbeincludedinthesimulation.Figure5showsthePSCADmodelofsynchronousmachinewiththeexcitermodelinplace?pnmerAFigure5:PSCADmodeltodemonstrateinitializationwithexciterAsexplainedinthepreviouscase,settheinitialterminalvoltagemagnitudeandphaseofthesynchronousmachineandoperateitasapuresource?Theterminalvoltagemagnitudeandphase,setwithrespecttoa'referencebus'(equivalentvoltagesource)ensuresthedesiredactiveandreactivepowerflow?TheexciterisinitializedatthetimeinstantwhenS2Mchangesstate?Thiscanbeensuredbysettingtheoutputcontrollerinitializationvariable(InitEx)(definedinthemachinemodel)asshowninFigure6?Thesamesignalnameisusedinsidetheexcitermodeltodefinetheinstantthatitshouldinitializeitsinternalparametersandoutputthedesiredfieldvoltage(Ef)valueasgivenbyEfO.-1SynchronousMdchmeI—哙TypeACExciter[O/txjtVariablesForConAckrInitatofonEGeneralSourccfO]toMachincfl]TransitionhtExLockedRotor(0]-Normal[i]TransitionEritGvGeneralOk||Help-Figure6:ControllerinitializationvariableFigure7showsthecontrolsignalstothesynchronousmachineandtheexciter.IntiaizationGrebes-Figure7:Controlsignals?Notethat,inadditiontothedesiredoutputfieldvoltagetothemachine(EfO),thefieldcurrent(If)andtheterminalvoltageandcurrent(VT/IT)areprovidedasinputstotheexcitermodel.PSCADthencalculatestheinitializedvalueoftherefereneevoltage’VrefO"needtomaintainthesteadystateoperatingcondition.VrefOisthe'initialized'voltagesetpointtomaintainthespecifiedsteadystateterminalconditions.Oncethesystementerssteadystate,asampleandholdcomponentcanbeusedtoholdthissteadystaterefereneevoltageandfeedthesignalbacktotheexciterthroughinput'Vref?Note1:Duringinitializationthemachineisoperatedaspuresource.Note2:Iftheuserneedstochangethevoltagereferencepointduringthesimulation,thiscanbeachievedthroughanexternal(variable)inputwhichisgivenazerovalueinitially,Figure8?VoltagerefereneeVoltagerefe...Figure8:optionforvariablereferencecontrolGovernorandturbineinitializationAftertheinitialtransientshavesettledthemachinemodewasactivatedbyswitchingS2Mfrom0to1.Atthisinstanttherotorwillbespinningataconstantspeedasthemachineisstillinlockedrotor*state.Thegovernorsandturbinescanbeinitializedatthetimeinstantwhentherotorisunlockedi.e.whenthesignalLRRisswitchedto1.Oncethishappensthemechanicaldynamics,asdefinedbyequation(1)isactive?Tm-Te=J^+Ba)m(1)Thesimulationmodelwithagovernor/turbinemodelisshowninFigure9.Thesemodelsare'initializecTinamannersimilartothatusedtoinitializetheexciter.Signal1nitGv"(Figure6)isthecontrolsignalusedtoactivatetheinitializationofthegovernorH^oraGori20Figure9:PSCADmodelforsynchronousmachineswithexciter,governorandturbines(PSCADcaseSMstudyOlB.pscx)SimulationresultsThevariationofthevariousmachineparameterswhenitisswitchedfromsourcetomachinemodeatt=2secandalsowhentherotordynamicsareactivatedatt=2.5secinshowninFigure10./J10V??-JoaJ⋯-10刃Q■VOLTAFigure10:SimulationresultsusinggovernorandexciterAtthepointintimewhenthemachinesarerunningfreeandtheexcitationandgovernorsystemsarestable,a"snapshotcanbetaken?Faultsanddisturbancescanbeappliedtothesystemwiththestart-upcommencingfromthe'snapshotfile'.PSCAD:RefertoPSCADcase:SM_study_01_A.pscxandSM_study_01_B.pscx